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BBC vs LS#/X Need Advice Please

Speaking of a world of numbers, I guess the dyno curves do not tell the "whole" story. LS3 is about 200 lbs lighter, and I have read in one my engine books that 500 lbs equates to about 45 hp and 0.5 secs in the quarter in a 3,500 lb chevelle that ran 12-13's.

So the LS3 has lower TQ down low (approximately 460 @ 3,000 rpm, we will give it 480 bc of its weight advantage), approximately 70 ft-lbs lower than the RJ or ATK with equivalent HP. @ 4,000 RPM it then takes off and has equivalent (more or less) tq as the two BBC's. @ 4,000 RPM it has about 50 less hp than the BBC's, but ends up with about 30-50 more by 5,000 RPM where the BBC's drop off, and it continues to make an extra 60 hp until its peak around 6,400 (peak HP around 640, remember I am giving it +20 bc of the weight factor, vs the ATK's 560ish at 5,100 & the RJ's 502 from 4800-5500).

So the LS3 is approximately 10% the under-dog at 3,000 RPM's, evens up in the 4's, & takes the lead in the 5,000s. I gotta think the engine will wind up quicker, bc of its higher peak RPM, will these two setups come out in a wash in the quarter with the BBC winning the 1/8th and the LS3 taking the 1/4 mile? Or is that too much of an assumption to make based upon curves alone? I mean we are running similar drivetrains, I got dana 60's with 5.38's, 38's or 38.5's, 700R4 (which will probably **** the bed once one of these guys gets dropped in).

I guess I could try to tabulate the #'s & drop them into the engine dyno and see what times it spits out for the quarters. I know that is not what our trucks are for, but that is really the only metric I can think of to evaluate the two engines.

Any ideas how to compare the in car performance with the information I have now?
 
I am calling the ATK vs RJ in the RJ's favor, bc I gotta think you can tune the extra bit of HP in, plus it is a newer BBC & has more low end torque. I have also read that changing the throttle body in conjunction of giving it the matching tune can give you an incremental 80 hp, hopefully not sacrificing the low end torque, for about $500.
 
Heres my take, the LS engines are awesome, and they make a lot of power for a small block, but they will always be small blocks. Big blocks make more torque and can make more power too when setup right. Yes if you put a supercharger on an LS is makes big power, but you know what happens when you put a supercharger and EFI on a big block? Insane power. The big block has more potential because it has more cubes, it's as simple as that. The LS will probably get better mileage.

They are both good engines, you just need to decide which one you want. I've ridden and driven a lot of LS vehicle and a lot of big block vehicles, big blocks still rule.

And for your bench racing, the rule of thumb for a typical street vehicle is 100 lbs = 10 hp = 0.1 seconds in the quarter. It's not linear but it's a good rule of thumb for most street cars. The faster you go the harder it is to go a little faster.

If I shoot 175 hp of nitrous in my car I pick up ~1.4 seconds in the quarter. If I shoot 100 shot I pick up a second. I run mid 10s on juice. If my cousins shoot 300 hp in their dragsters they only pick up a few tenths of a second, but they are already doing the quarter in the high 6s before they even spray it, spray puts them over 200 mph.
 
Sounds like the ECM, wiring harness and related stuff is extra cost on that. The 7.0 liter one i originally linked is ~600 hp and does include the ECM, retrofit harness and gas pedal. Total cost would be similar for both, but 80 hp more and more tq out of the 7.0.
 
If you want Ls info and prices call a guy named steve at snl performance there local to us and he can give you all the info you need.
970hp/1100tq on pump gas 408 and a whipple
 
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I think you maybe right good call. I have been in contact with blueprint engines about that engine. I am very close to buying that guy, assuming it comes with all the sensors and harness that I need to install. It is going to cost more for the engine, mounts and accessories, but it should make up for it with mpgs. However I could equally see myself with a ram jet. Ugghh, I should just flip a coin.
 
So regarding my hypothetical race scenario, you think the LS3 would stand up to the BBC?

If I go LS3 what else will I have to buy that I wouldnt with the BBC?
Motor Mounts?
Probably can reuse less accessories
Will have to upgrade fuel pump regardless
Will the LS3 require a radiator upgrade?
Does the LS3 limit my transmission setups? The jury is out, but it sounds like the 700R4 will not make it long. Sorry to whoever I told I had a 4L60E, I was wrong.
 
Nothing about these toy vehicles is cheap, and you'd be hard pressed to build an LS3 like that for less.
 
They have not listed it yet, the dyno chart is shown above in black and white. Dyno'd at 614hp @ 6500 rpm & 560 ft-lbs @ 5200 rpm, stays above 500 ft-lbs from 4150 & up. Supposedly weights only a little over 500 lbs, so that is about 300 lbs less than the RJ, so if you call that an extra 30 hp & tq or derate the ram jet by 30, and the LS3 has equal or higher output at almost all RPM's.

Here is a copy and paste from summit, they are rating at 580 hp & 560 ft-lbs.

These BluePrint Engines Pro Series Chevy LS 427 c.i.d. EFI retrofit dressed crate engines put down a whopping 580 hp and 560 ft.-lbs. of torque! They feature a 30-month/50,000-mile warranty and they are the perfect choice for drivable and reliable high-end performance. Additionally, BluePrint Pro Series Chevy 427 c.i.d. dressed crate engine assemblies are manufactured under strict tolerances and provide outstanding, consistent results. BluePrint Pro Series crate engines are also dyno-tested and include the dyno sheets.

Crate engine features include:

* New GM LS engine block
* 4340 forged 4.125 in. stroke crankshaft
* 4340 forged 6.125 in. long connecting rods
* Forged pistons
* 11.0:1 compression
* Hydraulic roller camshaft, .624 in. lift intake, .624 in. lift exhaust, 263 intake/exhaust duration @ 0.050 in. lift with 114 degree lobe separation
* Aluminum GM LS cylinder heads
* Double roller timing chain
* GM LS intake manifold, fuel injectors, fuel rails, drive by wire throttle body, and matching throttle pedal
* Full roller rocker arms
* Billet distributor
* Ignition coil packs
* Spark plug wires
* Spark plugs
* Harmonic balancer
* ECM with custom tune installed
 
A friend of my builds LS engines and for less then 10k he can do the same engine with all acc ready to drop in. No matter what, it's still not cheap. The LS is the way to go though and they are getting swapped into damn near everything now.
 
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